The issues seem to be that ./configure is setting IFS=' ' without unsetting the value again. This means tabs in CFLAGS also break ./configure. And the variables aren't escaped for config.mk.
This is not a proper patch only a proof of concept to fix the build of skalibs with newlines in CFLAGS: --- a/configure +++ b/configure @@ -59,12 +59,10 @@ EOF # generally not a good idea to use echo. # See http://etalabs.net/sh_tricks.html echo () { - IFS=' ' printf %s\\n "$*" } echon () { - IFS=' ' printf %s "$*" } @@ -133,8 +131,7 @@ iscached () if test -r "$tmps" && grep -q "^${1}: " "$tmps" ; then grep "^${1}: " "$tmps" | tail -n 1 | { - IFS=' ' - read -r k v ldlibs + IFS=' ' read -r k v ldlibs if test -n "$ldlibs" ; then echo " ... user-provided: $v with linker args: $ldlibs" echo "$ldlibs" >&3 @@ -705,7 +702,9 @@ CC := ${CC_AUTO} CPPFLAGS_AUTO := $CPPFLAGS_AUTO CPPFLAGS := $CPPFLAGS $CPPFLAGS_POST CFLAGS_AUTO := $CFLAGS_AUTO -CFLAGS := $CFLAGS $CFLAGS_POST +CFLAGS := $CFLAGS ${CFLAGS_POST//' +'/'\ +'} LDFLAGS_AUTO := $LDFLAGS_AUTO LDFLAGS := $LDFLAGS $LDFLAGS_POST LDFLAGS_NOSHARED := $LDFLAGS_NOSHARED
